1. Field of the Invention
In systems for processing stacks of articles in sheet form such as sheets of papers and then restacking the articles, the articles upon restacking assume a reverse order if the second article processed is stacked on the first and so forth. In order to avoid a reversal of order in the restacked articles, the articles are inverted after processing and then restacked. The result is that the first inverted article is restacked face down with the second inverted article face down on the first and so forth. The result is that after restacking, the original order is not reversed notwithstanding that the restacked stack has the first article on the bottom. Upon inverting the entire restacked stack, the resulting stack is in the same order as the stack preceding processing.
In systems for processing stacks of articles in sheet form, it is also desired to deliver the articles into selected ones of a plurality of hoppers while maintaining the original order of the articles.
In grading test answer sheets which are machine readable, a stack of test sheets are fed sequentially through a scanner apparatus which reads, scores, and records the test results. The score sheets after being scanned are stacked in a hopper in the reverse of the order of the test sheets originally delivered to the scanner apparatus. Since the test sheets are often rerun through the scanner apparatus as a check or because of a fault in scanning, it becomes necessary to restack the scanned test sheets to return the sheets from the reverse order or to the original order prior to a rescan. Such restacking is either done by hand or by running the stack of reverse order through the scanner apparatus without scanning to restore the original order.
2. Description of the Prior Art
It is known to invert sheets or documents after processing in xerographic machines and before placement in a tray or hopper in order to maintain the original order of the sheets or documents. Without inverting the sheets or documents, their original order becomes reversed when the sheets are placed sequentially in a tray or hopper one upon the other.
The apparatus of each of U.S. Pat. Nos. 4,469,323, 4,220,323, 4,040,616, and 3,615,129 invert sheets when moving in a downward direction for the purpose of restoring the original order of the sheets; however, the deflectors of such apparatus for inverting the sheets do not alone selectively direct the inverted sheets into a selected one of two hoppers. In the 4,469,323 patent, an array of secondary deflectors are utilized to direct the inverted sheet from a main deflector into one of a plurality of trays in a sorter. The apparatus of the 4,220,323 patent has only one hopper for inverted sheets while the deflector itself serves as a hopper for the univerted sheets. In the 4,040,616 patent, the deflector for inverting the sheets is held stationary while the hoppers of the sorter for receiving the sheets are moved. In the 3,615,129 patent, a movable deflector directs the sheets downwardly for inverting the sheets and placing the same in a hopper in a duplex xerographic process.
In U.S. Pat. No. 3,948,505, the direction of travel of the sheet is reversed. A movable gate inverts the sheet into either of two stacks as directed by the rotational position of a gate.
U.S. Pat. No. 3,700,231 shows a movable baffle which can direct sheets upwardly to place them in their original order on one tray or to permit the sheets to move downwardly and accumulate on another tray in reverse order.